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1. K.Devendra, T. Rangaswamy / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.2028-2033
Determination Of Mechanical Properties Of Al2O3, Mg (OH)2
And Sic Filled E-Glass/ Epoxy Composites
K.Devendra*, T. Rangaswamy**
*(Asst. Professor, Dept. of Mech. Engg., SKSVMACET, Laxmeshwar, KA, India,)
** (Professor, Dept. of Mechanical Engineering, GEC, Hassan, KA, India,)
ABSTRACT
In this research work, mechanical constituent materials (type, quantity, fibre
behavior of E-glass fiber reinforced epoxy distribution and orientation, void content). Beside
composites filled with varying concentration of those properties, the nature of the interfacial bonds
aluminum oxide (Al2O3), magnesium hydroxide and the mechanisms of load transfer at the interphase
(Mg(OH)2) and silicon carbide( SiC) were studied. also play an important role [4]. Now-a-days specific
Composites were fabricated by standard method. fillers/additives are added to enhance and modify the
The objective of this work was to study the quality of composites as these are found to play a
mechanical properties like ultimate tensile major role in determining the physical properties and
strength, impact strength, flexural strength and mechanical behavior of the composites. For many
hardness of the fabricated composites. The industrial applications of glass fiber reinforced
experimental results show that composites filled epoxy composite, information about their
by (10% Vol.) Mg(OH)2 exhibited maximum mechanical behavior is of great importance.
ultimate tensile strength and SiC filled Therefore, this work presents an experimental study
composites exhibited maximum impact strength, of the mechanical properties of E-glass fiber
flexural strength and hardness. reinforced epoxy composites filled by varying
concentration of Al2O3, Mg (OH)2 and SiC.
Key words: Composites, Fillers, Mechanical,
Properties, Strength 2. EXPERIMENTATION
2.1. MATERIALS
1. INTRODUCTION The composites were made from E-glass
There is an increasing demand for advanced fiber and commercially available ARALDITE (L-
materials with better properties to meet new 12) along with hardener K-6. Al2O3, Mg (OH)2 and
requirements or to replace existing materials. The SiC was used as filler materials. Aluminum oxide
high performance of continuous fiber (e.g. carbon particles is a ceramic powder commonly used filler,
fiber, glass fiber) reinforced polymer matrix it is also used as an abrasive due to its hardness.
composites is well known and documented [1]. Magnesium hydroxide is an inorganic compound
However, these composites have some and it is a white powder with specific gravity of
disadvantages related to the matrix dominated 2.36, very slightly soluble in water; decomposing at
properties which often limit their wide application 350o C. Magnesium hydroxide is attracting attention
and create the need to develop new types of because of its performance, price, low corrosiveness
composite materials. In the industry, the addition of and low toxicity. Silicon carbide exhibits favorable
filler materials to a polymer is a common practice. mechanical and chemical properties at high
This improves not only stiffness, toughness, temperatures for many applications. The benefits of
hardness, heat distortion temperature, and mold using SiC as reinforcement are improved stiffness,
shrinkage, but also reduces the processing cost strength, thermal conductivity, wear resistance,
significantly. In fact, more than 50% of all produced fatigue resistance, reduced thermal expansion and
polymers are in one way or another filled with dimensional stability.
inorganic fillers to achieve the desired properties [2].
Among the thermosetting polymers, epoxy resins are 2.2 FABRICATION OF COMPOSITES
the most widely used for high-performance The E-glass /Epoxy based composites filled
applications such as, matrices for fibre reinforced with varying concentrations (0, 10 and 15 Vol %) of
composites, coatings, structural adhesives and other aluminum oxide (Al2O3), magnesium hydroxide (Mg
engineering applications. Epoxy resins are (OH)2), and silicon carbide (SiC) were prepared.
characterized by excellent mechanical and thermal The volume fraction of fiber, epoxy and filler
properties, high chemical and corrosion resistance, materials were determined by considering the
low shrinkage on curing and the ability to be density, specific gravity and mass. Fabrication of the
processed under a variety of conditions [3]. composites is done at room temperature by hand lay-
Mechanical properties of fibre-reinforced up techniques. The required ingredients of resin,
composites are depending on the properties of the hardener, and fillers are mixed thoroughly in a basin
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2. K.Devendra, T. Rangaswamy / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.2028-2033
and the mixture is subsequently stirred constantly.
The glass fiber positioned manually in the open
mold. Mixture so made is brushed uniformly, over
the glass plies. Entrapped air is removed manually
with squeezes or rollers to complete the laminates
structure and the composite is cured at room
temperature.
2.3 SPECIMEN PREPARATION
The prepared slabs of the composite
materials were taken from the mold and then
specimens were prepared from composite slabs for
different mechanical tests according to ASTM
standards. The test specimens were cut by laminate
by using different tools in work shop. Three
identical test specimens were prepared for different
tests
2.4 MECHANICAL PROPERTY TESTING
Tensile, bending, impact and hardness tests
were carried out using Universal testing machine, Fig.1 Universal Testing Machine
impact machine and hardness testing machine
respectively. Three identical samples were tested for
tensile strength, bending, impact strength and
hardness.
2.4.1TENSILE STRENGTH
The tensile behavior of prepared samples
was determined at room temperature using Universal
testing machine in accordance with ASTM D3039.
Test specimens having dimension of length 250 mm,
width of 25 mm and thickness of 2.5 mm. The
specimen was loaded between two manually
adjustable grips of a 60 KN computerized universal
testing machine (UTM) with an electronic
extensometer. Each test was repeated thrice and the Fig. 2 Tensile strength test specimen
average value was taken to calculate the tensile
strength of the composites. 2.4.2 IMPACT STRENGTH
The charpy impact strength of composites
Details of Universal Testing Machine was tested using a standard impact machine as per
Make- Micro Control Systems ASTM E23 standard. The standard test specimen
Model- MCS-UTE60 55mm long 10 x 10mm2 cross section, having 450 V-
Software-MCSUTE STDW2KXP notch and 2mm deep were used for the test. Each
System uses add-on cards for data test was repeated thrice and the average values were
acquisition with high precision and fast analog to taken for calculating the impact strength.
digital converter for pressure/Load cell processing
and rotary encoder with 0.1 or 0.01 mm for
measuring cross head displacement (RAM stroke).
These cards are fitted on to slots provided on PC’s
motherboard WINDOW9X based software is
designed to fulfill nearly all the testing requirements.
MCS make electronic extensometer is used with a
extremely accurate strain sensor for measuring the
strain of the tensile samples.
Fig. 3 Charpy Impact Test Specimen
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3. K.Devendra, T. Rangaswamy / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.2028-2033
2.4.3 FLEXURAL STRENGTH GEA1 50 40 10%
Flexural strength is determined by 3-point Al2O3
bend test. The test specimen of dimension 130 mm × GEA2 50 35 15%
25mm×3.2 mm were used for test. This test method Al2O3
determines the flexural properties of fiber reinforced GEM1 50 40 10%
polymer composites. Mg(OH)2
Flexural strength is calculated by the following GEM2 50 35 15%
equation from the standard ASTM D 790 Mg(OH)2
𝟑𝐏𝐋
𝛔𝐟 = ------------------- (1) GESI1 50 40 10% SiC
𝟐𝐛𝐡 𝟐
Where GESI2 50 35 15% SiC
σf = Stress in the outer fibers at midpoint ( MPa)
P = Load at a given point on the load-deflection
curve (N) 3 RESULTS AND DISCUSSION
L = Support span, (mm) The ultimate tensile strength, impact
b = Width of beam tested, (mm) strength, flexural strength and Brinell hardness
h = Depth of beam tested, (mm number for different composition of composite
materials are presented in tables 2- 5 and their
variations shown in figures 5 to 8 respectively.
3.1 ULTIMATE TENSILE STRENGTH
The tensile strength of the composite
materials depends upon the strength and modulus of
the fibers, the strength and chemical stability of the
matrix, the fiber matrix interaction and the fiber
length.
Table 2: Comparison of Ultimate Tensile Strength
Composite Ultimate Tensile
materials Strength, (M Pa)
GE 450.24
GEA1 292.8
Fig. 4 Bending test specimen GEA2 257.21
GEM1 375.36
GEM2 347.2
2.4.4 BRINELL HARDNESS TEST GESI1 285
Brinell hardness test was conducted on the GESI2 224.53
specimen using a standard Brinell hardness tester. A
load of 250 kg was applied on the specimen for 30 From the obtained results it is observed that
sec using 5mm diameter hard metal ball indenter and composite filled by (10% Vol.) Mg (OH) 2 exhibited
the indentation diameter was measured using a maximum ultimate strength(375.36MPa) when
microscope. The hardness was measured at three compared with other filled composites but lower
different locations of the specimen and the average than the un filled composite this may be due to good
value was calculated. The indentation was measured particle dispersion and strong polymer/filler
and hardness was calculated using equation (2). interface adhesion for effective stress transfer but
further increase in filler content (up to 15 % Vol.)
𝟐𝐏 the tensile strength is found to be less this is due to
𝐁𝐇𝐍 = ----------------- (2)
𝛑𝐃 𝐃− 𝐃 𝟐 −𝐝 𝟐 more filler material distribution in the material.
Composites filled by Al2O3 exhibited better ultimate
Where: strength when compared with SiC filled composites.
P= Applied force (kgf) From the “fig.5” it is observed that increase in
𝐷 = Diameter of indenter (mm) addition of filler materials to composites leads to
𝑑 = Diameter of indentation (mm) decrease in ultimate strength this may be due to
more filler distribution and filler materials
Table 1: Designation of Composites dominated in the composite materials.
Material Glass Fiber Epoxy Filler
Designati (%Volume) (%Volu Materials
on me) (%
Volume)
GE 50 50 Nil
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4. K.Devendra, T. Rangaswamy / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.2028-2033
Fig.5 Ultimate tensile strength for different Fig. 6 Charpy Impact strength for different
composition of composite materials composition of composite materials
3.2 IMPACT STRENGTH 3.3 FLEXURAL STRENGTH
Impact strength is defined as the ability of a Comparison of the flexural strengths of
material to resist the fracture under stress applied at composite materials are shown in “fig. 7” they
high speed. The impact properties of composite indicated that composites filled by (10%Vol) SiC
materials are directly related to overall toughness exhibited maximum flexural strength (291.55MPa)
and composite fracture toughness is affected by inter when compared with other filled composites but
laminar and interfacial strength parameters. lower than the un filled composites this due to that
good compatibility between filler and matrix. The
Table 3: Comparison of Charpy Impact Strength reduction of flexural strengths is observed with
Composite Charpy Impact Strength increase in addition of SIC this may the fillers
materials ( J/mm2) disturb matrix continuity and reduction in bonding
strength between filler, matrix and fiber. However,
GE 0.2846 test results show that increase in addition of Al2O3
GEA1 0.16812 and Mg (OH2), enhances the flexural strength this is
GEA2 0.1575 due to uniform distribution of filler materials and
GEM1 0.16875 increased in effective bonding between filler
GEM2 0.1625 materials and matrix and strong polymer/filler
GESI1 0.3 interface adhesion.
GESI2 0.28
Table 4: Comparison of Flexural Strength
Experimental results is indicated that SiC Composite materials Flexural
filled composites having high impact strength when Strength (MPa)
compared with other filled composites this due to GE 326.83
that good bonding strength between filler, matrix GEA1 185.12
and fiber and flexibility of the interface molecular GEA2 240.96
chain resulting in absorbs and disperses the more GEM1 241.06
energy, and prevents the cracks initiator effectively. GEM2 264.87
The energy absorbing capability of composites GESI1 291.55
depends on the properties of the constituents, based GESI2 280.84
on literature review it is found that the benefits of
using SiC as reinforcement are improved stiffness,
strength and chemical stability. Composites filled by
(10% Vol) Al2O3 and Mg (OH)2 exhibited good
impact strength but increase in addition of Al2O3 and
Mg(OH)2 leads to decrease in impact strength .
Typically, a polymer matrix with high loading of
fillers has less ability to absorb impact energy this is
because the fillers disturb matrix continuity and each
filler is a site of stress concentration, which can act
as a micro crack initiator and reduces the adhesion
and energy absorption capacity of composite
materials this is observed in composites filled by
(15% Vol.) Al2O3 , Mg(OH2 ) and SiC.
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5. K.Devendra, T. Rangaswamy / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.2028-2033
4 CONCLUSIONS
In the present research work E-glass/Epoxy
based composites filled with varying concentrations
of Al2O3, Mg(OH)2 and (SiC) were prepared.
Fabrication was conducted at room temperature by
hand lay-up techniques. Based upon the test results
obtained from the different tests, several important
conclusions can be drawn.
From the obtained results composite filled
by (10% Vol.) Mg (OH)2 exhibited maximum
ultimate strength (375.36MPa) when compared with
other filled composites but lower than the un filled
composite this may be due to good particle
dispersion and strong polymer/filler interface
Fig. 7 Flexural strength for different composition of adhesion for effective stress transfer. Increase in
composite materials addition of filler materials to composites leads to
decrease in ultimate strength this may be due to
3.4 HARDNESS more filler distribution and filler materials
Hardness numbers of all the composites are dominated in the materials. Experimental results
presented in the table-5 indicated that SiC filled composites having high
impact strength when compared with other filled
Table 5: Comparison of Brinell hardness number composites this due to that good bonding strength
Composite Brinall Hardness between filler, matrix and fiber and flexibility of the
materials Number (BHN) interface molecular chain resulting in absorbs and
GE 57.64 disperses the more energy, and prevents the cracks
GEA1 73,90 initiator effectively. The flexural strength results
GEA2 82.13 indicated that composites filled by (10%Vol.) SiC
exhibited maximum flexural strength (291.55MPa)
GEM1 88.69
when compared with other filled composites but
GEM2 88.10
lower than the un filled composites this due to that
GESI1 72.46
good compatibility between filler and matrix.
GESI2 91.73 However, test results show that increase in addition
of Al2O3 and Mg (OH2), enhances the flexural
The experimental results indicated that strength this is due to uniform distribution of filler
composite filled by (15 % Vol.) SiC exhibited materials and increased in effective bonding between
maximum hardness number (91.73BHN) this due to filler materials and matrix and strong polymer/filler
uniform dispersion of SiC particles and decrease in interface adhesion. Composite filled by (15 % Vol.)
inter particle distance with increasing particle SiC exhibited maximum Brinell hardness number
loading in the matrix results in increase of resistance (91.73 BHN) this due to uniform dispersion of SiC
to indentation. From the obtained results it is particles and decrease in inter particle distance with
observed that increase in addition of Al2O3 increases increasing particle loading in the matrix results in
the hardness of the composites. Composites filled by increase of resistance to indentation.
Mg (OH)2 exhibited better hardness number when
compared with Al2O3 filled composites this may be
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6. K.Devendra, T. Rangaswamy / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
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